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The purpose of this research is to assess the potential of using coal ash for restoring Acid Mine Drainage. For this purpose, we decided to determine the physical-chemical composition of the coal waste, coal ash and effluent, where physical and chemical parameters were assessed. Mineralogical characterization of tailings was carried out, where quartz, kaolinite, siderite, palygorskite, muscovite and dolomite were verified. Geochemical characterization of coal ash was also done, where found Si, Al, Fe, K, Ca, Ti as the main elements and presence of Cu, Cr, Zn, Rb, Ir, Mn, As, Y, Pb, Nb, Th as trace elements, being defined by the X-Ray Diffraction and X-Ray Fluorescence method. The dynamic and the static of Fizz test methods were used, which showed the maximum time of absorption for H+ ions from the activation of ashes in the effluent. Satisfactory results were obtained after calcination, since the main acid-generating elements contained in the fine residues were converted to trace elements. The pH of the ashes was found to be neutral. It is concluded that coal ashes from fine coal tailings have the power to restore the Acid Mine Drainage.

Acid mine drainage (AMD) or acid rock drainage (ARD) refers to the effluents from coal and metal mines. AMD is a common phenomenon which occurs naturally as a process of rock weathering, but is increased in large scale due to human activities such as construction contracts (transportation corridors, dam build, etc.) and mining operations. This phenomenon denotes the acidic water that is produced during exposure of sulphide minerals (mainly pyrite) to air and water through a natural process, and creates sulphuric acid. AMD is a hazard to animals, aquatic life and human beings as it increases the acidity and dissolves metals. Preventing and treating AMD is an important issue in a mine site not only during operation life but also after the mine is abandoned.

Intensive mining and processing of the polymetallic sulfide ore body of Cerro Rico de Potosí (Bolivia) has occurred since 1545. To further investigate acid mine drainage (AMD) discharges and their link to downstream contamination, data were gathered during two sampling events during the most extreme periods of the dry and wet seasons of one year. Concentrations of Ag, B, Ba, Mo, Sb, Se, Sn and V in AMD and receiving streams were greater than Bolivian discharge limits and receiving water body guidelines as well as international agricultural use standards. High concentrations of rare earth metals have been documented in this area. Results indicate that contamination from mining has a larger scope than previously thought and underscore the importance of remediation.

Acid mine drainage generated from coal mine showed a pH of 3.2, high concentrations of SO4(2-), Al, Fe, Mn, Zn and minor As, Cd, Co, Cr, Cu, Ni and Pb. The major reduction in the concentration occurred for Al, As, Cr, Fe and Pb after the treatment with CaO. The evolution of these acid waters within the tributary stream showed decreasing concentration for all soluble constituents, except Al. This natural attenuation was controlled by pH (6.4 to 10.8) as a result of concurrent mixing with tributary stream and reaction with local bedrock that contains limestone. Aluminum increasing concentration during this evolution seems to be related to an input of Al-enriched waters due to the leaching of silicate minerals in alkaline conditions.

Acid drainage results from exposition of sulfides to the atmosphere. Arsenopyrite is a sulfide that releases arsenic (As) to the environment when oxidized. This work evaluated the As mobility in six sulfidic geomaterials from gold mining areas in Minas Gerais State, Brazil. Grained samples (

Zeolitic material was synthesized from coal fly ashes (baghouse filter fly ash and cyclone filter fly ash) by hydrothermal alkaline activation. The potential application of the zeolitic product for decontamination of waters from acid mine drainage was evaluated. The results showed that a dose of 30 g L-1 of zeolitic material allowed the water to reach acceptable quality levels after treatment. Both precipitation and cation-exchange processes accounted for the reduction in the pollutant concentration in the treated waters.

Six sulfide-bearing, flotation tailings dams and one waste-rock dump from epithermal Pb-Zn-Ag-Cu deposits in Taxco, Guerrero have been mineralogically and geochemically characterized to evaluate their potential environmental impact. Primary phases are dominated by quartz and rock fragments with scarce feldspar, barite and ferromagnesian. Calcite is found in the less oxidized tailings. Primary sulfides are pyrite and sphalerite with some pyrrothite, galena, chalcopyrite, Ag-sulfosalts and arsenopyrite. In oxidized zones, sulfides are low or absent. Secondary phases are widespread and include gypsum, chalcocite, keoheite, nimite, hetaerolite, jarosite, smithsonite, bernalite, epsonite, rozenite, pickeringite, hexahydrite, bassanite, boyleite, hematite, scorodite, cryptocrystalline and amorphous precipitates and poorly crystallized Fe-oxyhydroxides. EDS analysis suggests that adsorption is important in the retention of metals.All Taxco tailings and waste-rock dumps show high concentrations of total Ag (9.5 74.2 mg/kg), Cd (1.0-780 mg/kg), Cu (71.8-1320 mg/kg), Fe (2.49-25.1%), Mn (18.6-13 800 mg/kg), Pb (780-43 700 mg/kg), V (2.0-127 mg/kg), Zn (380->10 000 mg/kg) and As (19.0-11 800 mg/kg) exceeding the regional background concentrations in crop soils. Contents of water-soluble metals are heterogeneous but contain significant amounts of toxic metals (e.g. Cd = 0.025-1105 mg/L; Pb =